The invention relates to a sprayable dispersion based on an acrylic acid ester copolymer and a colloidal chloroprene polymerisate. The invention also concerns a process for the elastic adhesion of two substrate surfaces, of which at least one is porous in structure, using this dispersion. Here and below the term acrylic acid ester copolymer also comprises an acrylic acid ester styrene copolymer.
Acrylic acid ester copolymers are for example the substances ACRONAL 310S, S600 or DS3382 by the company BASF, chloroprene polymerisates are the substances DISPERCOLL C74 or C84 by the company BAYER.
When two substrate surfaces are coated with an adhesive and pressed together after the adhesive has dried, the adhesive is called a contact adhesive. This can only develop its effect when the solvent or water has evaporated. If only one of the two substrate surfaces to be joined is coated with an adhesive and the other substrate surface pressed on after evaporation of the solvent or water, we have a bonding adhesive. Of particular importance are contact adhesives based on polychloroprene, resins and organic solvents. The solid content is usually only 10-25 w. %, the organic solvents predominate by far.
Contact adhesives dissolved in highly volatile organic solvents can be processed quickly. This advantage is however largely or even predominantly eliminated by a number of disadvantages. The organic solvents which escape on spraying and drying represent a significant loss in economic terms. The volatile solvents are also inflammable, harmful to health and/or the environment. Therefore special systems must always be constructed and precautions taken to prevent or at least reduce the uncontrolled escape of solvents. EP, A1 0470928 describes a process for elastic adhesion of two substrate surfaces. At least one of these is porous in structure. A rubber-containing first dispersion with an acrylic acid ester copolymer and a colloidal second dispersion of a chloroprene polymerisate are applied to at least one of the substrate surfaces after prior or with simultaneous mixing. The substrate surfaces to be glued are then, immediately afterwards or later, laid against each other with the adhesive dispersions wet, and pressed together. The two substrate surfaces adhere with a high initial force even at room temperature and achieve a high final force. No organic solvents are required, but only low quantities of waste water occur which can easily be cleaned and disposed of. The spectrum of applications is broad but lies in particular in the adhesion of foams.